1. Field of the Invention
The present invention relates to an apparatus and method for displaying a three-dimensional image according to the position of a user and, more particularly, to an apparatus and method for displaying a three-dimensional image according to the position of a user, in which the distance between a display panel displaying a two-dimensional image and a three-dimensional optical panel converting a two-dimensional image into a three-dimensional image is controlled in accordance with the position of the user to provide an optimized three-dimensional image.
2. Description of the Related Art
With demands of users who desire to view images of improved picture quality, a digital TV has been developed. The digital TV provides improved picture quality and vivid images by adopting an aspect ratio different from that of an existing analog TV.
Picture quality is significant for a two-dimensional image whereas demands of users toward a three-dimensional image are recently increasing and studies of the three-dimensional image are being actively pursued.
Examples of a method of displaying a three-dimensional image include a glasses type method and a glasses-free type method. The glasses type method allows users to view three-dimensional images only if the users wear three-dimensional glasses while the glasses-free type method allows users to view three-dimensional images displayed in the screen without wearing the three-dimensional glasses. The glasses type is classified into a polarization type and a time-division type while the glasses-free type is classified into a parallax barrier type and a lenticular lens type.
Although existing three-dimensional image display systems have been developed in Japan, Europe, the United States of America, and others, for several years, their commercial use has been delayed due to visual fatigue and the inconvenience of wearing three-dimensional glasses.
Examples of visual fatigue generated in the three-dimensional image systems include accommodation-convergence breakdown and crosstalk.
The accommodation-convergence breakdown allows a user to recognize a three-dimensional depth without fatigue as accommodation-convergence is made when the user actually views an object. However, if the user views a three-dimensional image through the existing three-dimensional image system, accommodation-convergence breakdown occurs due to great disparity. In other words, eyes of the user focus on a plane of the screen while converging on a three-dimensional position created by the disparity on the screen, whereby discrepancy is caused.
Even though images having a depth exceeding a focal length of the user's eyes exist, they are displayed with definition, whereby such double images fatigue the user's eyes.
Crosstalk occurs as left and right images are not exactly delimited from each other in the three-dimensional image display system. Also, crosstalk occurs due to incomplete image conversion of the three-dimensional glasses or afterglow effect of a light-emitting factor on a monitor. Moreover, even though left and right images are exactly delimited from each other, their delimitation depends on the position of the user. In this case, crosstalk may still occur.
Unexamined Korean Patent Publication No. 2004-026693 discloses a display device including a three-dimensional image source, a disparity barrier arranged between the image source at one side and a lenticular lens at the other side, having a light-transmittive slit array for transmitting light beams to an array of lenticular lenses, and a control device controlling the slits of the disparity barrier to detect view point positions and vary an incident angle using a parameter value.
However, the slits of the parity barrier require delicate motion to display the three-dimensional image. It is not easy for the above related art to realize such delicate motion of the slits using an electric or magnetic method. Also, the above related art fails to disclose or describe motion of the slits. In this regard, a three-dimensional image display system is required, which can provide proper disparity according to a user's position.